The phrase "mountainous regions" refers to areas that are characterized by high elevation, steep slopes and rugged terrain. These regions typically feature landforms such as hills, peaks, cliffs, valleys, canyons and other geological formations created by the forces of tectonics, erosion and weathering over millions of years. Mountainous areas are often home to unique ecosystems that support a diverse range of plant and animal life, many of which are adapted to high altitude environments. The phrase can also be used in a more general sense to describe any region with challenging terrain or topography.